Insulator compartment



1 c. w. J. HEDBERG INSULATOR COMPARTMENT Filed June 5, 1935 a J y g 1 ll l l 4 Stream Patented Nov. 16, 1937 UNITED STATES PATENT OFFICEaosaosa INSULATOR, COMPABTMENT Application June 5, 1935, Serial No.25,192

6 Claim.

This invention relates to an improvement in insulator compartmentsassociated with electrical precipitator chambers, and is particularlydirected to an improved method of inspecting and cleaning such insulatorcompartments and to an improved insulator compartment structure.

In electrical precipitators the discharge electrodes are generally athigh tension, while the collecting electrodes and the precipitatorstructure as a whole are grounded. This necessitates the provision ofhigh tension insulators for bringing the high tension conductors intothe precipitator chambers. The insulators arecommonly contained inprotective housings forming compartments which are isolated from themain gas flow and are frequently heated in order to keep the insulatorsas dry as possible. In spite of these precautions the insulatorsrequire-frequent cleaning and inspection, as the industrial gasestreated by electrical precipitation are dirty and frequently saturatedwith water, acids or other liquids.

The provision of a liquid seal between the precipitator chamber and theinsulator compartment is unsatisfactory. Such seals are diillcult tomaintain and add to the possibility of contaminating the insulator,particularly because of fluctuations in the pressure of the gas beingtreated which cause the liquid to slop out of the seal and also becausethe liquids rapidly become contaminated by the dirt and corrosive agentspresent in the gas being treated.

It has, therefore, been the general practice to provide freecommunication between the precip= itator chamber and the insulatorcompartment. Whenever insulators associated with precipitatorscontaining explosive or toxic gases require inspection or cleaning, itis necessary to purge out the entire precipitator chamber to avoiddanger of explosion and harmful effects on the workmen. This procedurenot only wastes all of the gas contained in the precipitator, butnecessitates a considerable delay in the operation of the precipitator.Because of the relatively large size of the precipitator chambers theoccasional formation of explosive mixtures is difiicult to avoid.

It has now been found that these disadvantages may be eliminated byproviding means for interrupting communication between the insuiatorcompartment and the precipitator chamher, and when inspection orcleaning of the insulator compartments is desirable, interrupting thecommunication by the means provided, opening insuiator compartment theair, and

conducting the inspection and cleaning without aflecting the gases inthe precipitator chamber. Before or after the insulator chamber isopened to the atmosphere it may be purged, for exam- .ple, by blowingsteam or carbon dioxide therevention; and

Fig. 2 is a plan, in partial section, on the line 2-2 of Fig. 1.

In the drawing, l is the shell of the precipitator chamber and 2 is theshell of the insulator compartment. High tension conductor 3 is broughtinto the compartment through insulating bushing 4', which projectswithin supporting insulator I, and connects with bus bar 5, preferablyutilizing a conductor, not shown, passing through the top of insulator 4to flange 40 and metallic supporting member 4i. Bus bar 5 supportsdischarge electrodes, not shown, within shell I. The bus bar passes intothe precipitator compartment through opening 6 and is surrounded at thispoint by a collar 1 to prevent corona discharges.

The insulator compartment is advantageously heated during operation, forexample, by means of steam, coil 8. The compartment is drained at 9. Ahinged cover plate H] is fastened by any convenient means, for example,by yokes H and bolts I2. An inlet conduit I3 is advantageously providedfor the introduction of purging gases.

Attached to the upper portion of shell 2 is an annular cup member I l,and attached to the insulator or conductor is a circular curtain memberl5 depending into the cup member. The cup member is provided withfilling and draining connections at l6 and with an overflow outlet at H.A vent I8 may be provided in the cover of the insulator compartment.

When it is desired to clean or repair an insulator in a compartment asdescribed, valve means in the gas inlet and in the gas outlet of theprecipitator are closed and the energizing current is shut on. The gasin shell I is then brought'to approximately atmospheric pressure so thatno appreciable difierence of pressure will exist across the liquid sealwhen door ii]! is opened. This is. accomplished by bleeding gas toatmosphere 1 through a valve, not shown, on pipe it, if the gas pressurein the shell at shut down is above atmospheric pressure. If the pressurein the shell is below atmospheric pressure, purging gas (which may beair, under some circumstances) is introduced through pipe it until thepressure within insulator compartment 2 and shell is raised to that ofthe atmosphere. Gaseous communication between this compartment and theprecipitator is cut off by running liquid into cup Ml through pipe it upto the overflow level. Door ill may then be opened. After the gases inthe insulator compartment have sumciently diffused into the atmosphere,assisted, if desired, by means of a purging gas introduced through it,the compartment may be inspected and cleaned and any necessary repairsmade without danger of the leakage of gas into or out of theprecipitator chamber. Thereafter the door it may be closed, the liquiddrained out of cup Ml through pipe l6 and it, and the precipitator againput into operation.

If the operating pressure of the gas in shell 9 is not more than, say,-2 inches of water above or below atmospheric, the seal can be filledwith insulating liquid, the insulator compartment purged out, and doorit can be opened for inspection of the insulator without stopping thegas flow or discontinuing the electrical treatment. Care must be taken,of course, to remain at a safe distance from members maintained at highpotential and to purge efiectively before opening door it and againafter closing door it and before draining seal cup M if explosive gasesare in- I volved.

It will be seen that the new method of operation and construction of theinvention provide a valuable improvement in the design and operation ofelectrical precipitation equipment and that the details of operation anddesign may be varied to a large extent, without departing from theprinciples of the invention.

I claim:

1. In association with an electrical precipitator chamber, an'insulatorcompartment including a housing, a. conductor mounted in an insulatinghousing, a conductor mounted in an insulating aocaoce a bushing memberscarried by said housing and said conductor, respectively, providing acup and .curtain cooperating to seal the insulator compartment fromtheprecipitator chamber when the cup contains a'liquid, means forsupplying liquid to said cup, means for draining liquid from said cup,meansfor passing a stream of purging gas into said compartment, andmeans for withdrawing the purging gas stream from said compartment.

3. In association with an electrical precipitator' chamber, an insulatorcompartment including a ment to the atmosphere for inspection and cleanaing.

4. In association with an electrical precipitator chamber, an insulatorcompartment including a housing, a conductor mounted in an insulatingbushing, a cup member carried by said housing and a curtain membercarried by said conductor, said cup and curtain cooperating to seal theinsulator compartment from the precipitator chamber when the cupcontains a liquid, means for supplying liquid to said cup, means fordrainingliquid from said cup, means for passing a stream .of purging gasinto said compartment, and means for withdrawing the purging gas streamfrom said compartment.

5. In association with an electrical precipitator chamber, a housingforming an insulator compartment, an insulator mounted in said housing,electrode supporting means mounted on said insulator, means for shuttingoff gaseous communication between the insulator compartment and thechamber, and means for opening said compartment to the atmosphere forinspection and cleaning.

6. In association with an electrical precipitator chamber, an insulatorcompartment including a housing, a conductor mounted in an insulator,members carried by said housing and said conductor, respectively,providing a cup and curtain cooperating to seal the insulatorcompartment from the precipitator chamber when the cup contains aliquid, means for supplying liquid to said cup, means for drainingliquid from said cup, means for passing a stream of purging gas intosaid compartment, and means for withdrawing the purging gas stream fromsaid compartment.

CARL W. J. HEDBERG.

dill

